This invention relates generally to footwear and is particularly concerned with footwear having shock absorbing or cushioning properties, and to methods of manufacturing such footwear.
Numerous shoe and other footwear designs have been proposed in the past for absorbing shock and adding lift, particularly in the athletic shoe field. U.S. Pat. No. 4,817,304 of Parker et al. describes footwear with a cushioning sole structure in which a sealed internal member in the sole is inflated with gas to form a resilient insert in the heel region of the shoe. Various shoe structures have been proposed in the past in which springs are embedded in the shoe sole in the heel region or over the entire sole, as shown, for example, in U.S. Pat. No. 5,138,776 of Levin, U.S. Pat. No. 4,566,206 of Weber, and U.S. Pat. No. 4,592,153 of Jacinto. Some of these structures are relatively bulky and heavy, and could not effectively be manufactured.